Electronically Controlled Electromechanical Valve

ABSTRACT

An electronically controlled electromechanical valve having at least three ports through which a fluid can flow and at least three different stable positions in which at least two ports are in fluid communication. The valve includes a stationary outer housing including at least three bores; a translating inner section that translates about an axis and includes adequate bores defining, with the bores of the housing, the at least three ports of the valve; and an electrical actuating system controlled by an electronic controller and configured to switch the valve from one position to another by translating the inner section along its axis. A fuel system vapor management unit includes such a valve.

The present invention relates to an electronically controlledelectromechanical valve and to a fuel system vapor management unitcomprising such a valve.

Electronically controlled valves are well known and often used inseveral technical fields like automotive and aircraft engine and fuelsystem vapor management. Such valves usually have two or three ports.Three port valves are advantageously used instead of two separate twoport valves when such valves have at least one port in common, in orderto have a more compact and simple design. However, such valves usuallyhave only 2 positions (each of them connecting 2 of the 3 ports).

For instance, U.S. Pat. No. 6,382,191 discloses a fuel tank pressurecontrol system which includes an electronically controlled valveassembly able to either connect the fuel tank and the canister only (fortank venting during normal operation and refueling), or the canister andthe engine only (for purging and burning the fuel vapors adsorbed on thecanister). This system, which closes the communication between the fueltank and the canister when the latter is connected to the engine,prevents too rich air/fuel mixtures from entering the engine and hence,prevents unburned hydrocarbons. The valve assembly used therein caneither be constituted of 2 separate 2 port valves, or of only one single3 port valve. The choice of 2 separate 2 port valves offers theadvantage of being able to selectively and progressively control thepurge flow, while simply turning on and off the tank venting valve. Thechoice of a regular, single three port valve does not allow thatfeature, but offers the advantage of a compacter and simpler design.

Therefore, it is an object of the present invention to provide anelectronically controlled electromechanical valve, able of controllingtank venting during normal operation and refueling, and canister purge(i.e. recovered fuel vapors entry into the engine from the canister),which valve offers a compact and simple design while allowing at leastone intermediate position for having an intermediate purge flow.

Accordingly, the present invention concerns an electronically controlledelectromechanical valve having at least three ports through which afluid can flow and at least three different stable positions in which atleast 2 ports are in fluid communication, said valve comprising:

-   -   a stationary outer housing comprising at least four bores;    -   a translating inner section which slides along an axis and        comprises adequate bores defining with the bores of the housing,        the at least three ports of the valve; and    -   an electrical actuating system being controlled by an electronic        controller and being able to switch the valve from one position        to another by sliding the inner section along its axis.

This integrated valve is designed in an axial fashion, which allows fora simple and compact system. In addition, it allows not only the twotraditional positions connecting each completely 2 of the 3 ports, butalso at least an additional one, for instance allowing only partialcommunication between 2 of the 3 ports.

Other advantages of this integrated valve are:

Lower Cost—This valve, which replaces 2 separate valves and associatedpiping system, reduces the total part count and hence, the cost of asystem in which it is used.

Quieter Product—Less noise comes from a valve that does not have to usepulse width modulation to control fluid flow, as it is the case withvalves equipped with a linear solenoid actuator (the latter cycles thevalve open and closed to vary the flow restriction according to theengine control unit (ECU) and this often results in undesirable noise).

Digital Control Capability—A digitally controlled component is, in mostoccasions, easier to integrate into a microprocessor.

The valve according to the invention may be of any material (orcombination of materials). It may be partially or totally made of metaland/or plastic(s). It preferably comprises polyacetal and may alsocomprise polyethylene at least in part of its surface in the case it ismeant to be fixed by welding to a polyethylene fuel tank. Alternatively,it may be fixed mechanically (through a nail, screw . . . ) to the fuelsending unit flange.

The valve according to the invention has a stationary outer housing andan inner translating section. The inner translating section is generallyof a substantially cylindrical shape, the axis of the cylindercorresponding to the axis of translation of that part. The shape of thestationary outer housing is less critical but is generally substantiallycylindrical as well. By “substantially cylindrical”, it is meant that asubstantial portion thereof is cylindrical, which does not exclude partsand/or appendices extending outside the generally cylindrical form (inthe case of the housing, like electrical and fluid connections forinstance).

The stationary outer housing comprises at least four openings (or bores)through which a fluid can flow and which define with adequate bores inthe inner translating section, at least three ports or passages throughwhich a fluid can enter or exit the valve. According to someembodiments, the valve may comprise a fourth and even a fifth portallowing more fluid communication possibilities. In that case, in someposition(s) of the valve, more than 2 ports may be into fluidcommunication.

The above mentioned bores and ports may have any shape and locationinside the housing and the inner section. These shapes and locations aregenerally adapted to the shape and location of the fluid lines to whichthe ports will be connected.

The valve according to the invention has at least 3 stable positions,i.e. discrete positions in which at least 2 ports are in fluidcommunication and to which the valve switches from one to another inresponse to an electrical actuating system being controlled by anelectronic controller. These 3 positions are advantageously such that 2of them allow complete fluid communication between at least 2 ports andthe third one allows only partial fluid communication between 2 ports.There could also be more than one intermediate position for having morethan one partial flow between 2 given ports. Besides, the valve may alsocomprise an additional closed position, in which none of the abovementioned 3 ports are in fluid communication, and which is held by asuitable default mechanism (like a spring for instance) able to ensurethat the system is sealed in the event of electrical power loss.

In one embodiment of the present invention, the electrical actuatingsystem comprises at least two coils fixed on the outer stationaryhousing and at least one magnet fixed on the inner translating section,the coils being coupled to a power generator which is able to energizethem, i.e. to generate an electrical current and make it circulatethrough them, in response to a signal from the electronic controller. Inthat case, each position of the valve is associated with a given coilbeing energized and attracting the magnet to it. In some cases,depending on the geometry and/or location of the fluid lines to beconnected to the valve, it may be advantageous to use at least twomagnets in order to allow for a quicker switch from one valve positionto another as well as the desired number of positions to allow forpartial communication between the engine and the canister. According toanother embodiment of the present invention, the electrical actuatingsystem comprises a separate actuator (motor), placed on the end of thevalve, which translates the inner section of the valve and puts it ingiven positions in response to a signal from the electronic controller.One embodiment of a motor drive includes a servo or stepper motorattached to a lead screw, inserted into the valve along the axis oftranslation. A matching nut is attached to the inner translating member,such that rotation of the servo or stepper motor translates the innermember within the component. In this case, it may be necessary to havemultiple position feedback sensors on the valve body. These sensors areused to determine the position of the inner translating member inrelation to the outer stationary member.

The use of such sensors is interesting in the event that the part istranslated by an external source (as explained above) but also, with thecoils system explained earlier, in the event of a power failure, inwhich the orientation of the part is not remembered.

The valve described above gives good results when used in a fuel systemvapor management unit of an engine (and more particularly, of aninternal combustion engine), especially if used in a unit similar to theone described in the above mentioned US patent. In that case, oneposition of the valve ensures complete flow communication between a fueltank and a vapor recovery system and the 2 other ones ensurerespectively complete and partial communication between this vaporrecovery system and the engine. In addition the valve allows forisolation of the fuel system to limit vapor generation. The vaporrecovery system is generally a charcoal canister, which adsorbshydrocarbons from the tank though vapor vent lines allowing the tank tovent (during normal operation including filling) without sendinghydrocarbons into the atmosphere. The hydrocarbons trapped in thecanister are periodically routed to the engine for combustion, in anamount depending on the rotational speed of the engine and being meteredwith the valve according to the invention. This amount goes from zerowhen the engine is switched off (and when only the fuel tank and thecanister are in total communication) to a maximum amount when the engineturns at a normal speed (and when only the canister and the engine arein total communication), and through an intermediate amount when theengine is turning at idle speed (and only the canister and the engineare in partial communication).

An additional feature that is often present in fuel system vapormanagement units is a vapor communication between the fuel tank and thefiller pipe. In many cases it serves three functions. First it allowsvapor in the fuel tank to be recirculated into the filler pipe andre-liquefied, thus minimizing vapor generation during refueling. Second,it serves as the communication path between the tank and the filler pipeduring leak detection diagnostics. Finally, in a crash situation, thefiller cap is often relied on for relieving any pressure incurred uponimpact via an over pressure valve. For this reason as well, there needsto be an open communication between the fuel tank and the filler pipe.The use of a valve according to the present invention can solve thisproblem as well, provided that said valve is equipped with at least anadditional port to be connected to a vapor recirculation line extendingto the filler pipe.

In recent times however, there has been a push to restrict the size ofthe vapor recirculation line to control the amount of vapor that entersthe filler pipe during refueling, thus minimizing the amount thatescapes into the atmosphere. This creates a contradiction between therefueling function and the pressure relief function. Therefore, it isnowadays generally preferable to have both a vapor recirculation linewith a large diameter (for unrestricted vapor recirculation to thefiller pipe) and one with a smaller diameter, to have a restricted vaporrecirculation flow during refueling. Alternatively, there could be onlyone vapor recirculation line but the access to it could be eitherthrough a port of large diameter or through a port of smaller diameter.Accordingly, in a preferred embodiment, use is made of a valve asdescribed above which comprises at least four ports for being connectedrespectively to the fuel tank, to the canister, to the engine, to apassage of large diameter to a vapor recirculation line and to a passageof small diameter to the (or another) vapor recirculation line, themanagement of which ports to be in fluid communication being performedby an electronic controller. It may be advantageous however to at haveat least 2 ports for being connected to the fuel tank in order toseparate venting and vapor recirculation function, i.e. one port ismeant for establishing fluid communication with the canister and theother one, with the filler pipe. In such a valve, more than 2 ports maybe in fluid communication in some position(s) of the valve.

Some preferred embodiments of the present invention will be explained inmore detail through FIGS. 1 to 5. FIGS. 1 to 4 relate to a threefunction 4 port valve which can be used in a fuel system vapormanagement unit both for venting of the fuel tank during refueling andnormal operation, and for purging the canister, also the vaporrecirculation function. FIG. 5 pictures an entire vapor managementsystem using this valve.

FIG. 1 shows one embodiment of the above described invention. An innermember (1) translates within an outer housing (2), via an actuator suchas but not limited to a solenoid or a stepper motor (not pictured)attached to either end of the outer housing (2). The outer housing (2),has four ports. The first port (3) provides fluid communication to thefuel tank. The second port (4) is in fluid communication with the vaporstorage canister. The third port (5) is in fluid communication of thefill head via a vapor recirculation line. The fourth port (6) is influid communication with the engine intake manifold.

FIG. 2 shows the valve positioned such that there is fluid communicationbetween the vapor recovery canister and the fuel storage tank. Thisposition is held by energizing a coil and attracting a magnet adjacentto it (both not shown). In this position, the vapor recirculation lineis in restricted communication between the tank and the filler pipe tocontrol the amount of vapor that is reintroduced to the filler pipeduring refueling.

FIG. 3 shows the valve in a “closed position”, which in this case meansleaving no fluid communication between the fuel tank, the canister andthe engine intake manifold. However, in this position, there is fullcommunication between the fuel tank and the filler pipe through thelarge diameter vapor recirculation line in anticipation of leakdiagnostics or a crash situation. This position is held via a spring(not pictured) to ensure that the system is sealed in the event of apower loss. In addition, this position will be used during driving toprevent fuel from contaminating the vapor recovery canister.

FIG. 4 shows the valve positioned such that there is fluid communicationbetween the vapor recovery canister and the engine intake manifold. Inthis position, there is no fluid communication between the fuel tank andthe filler pipe. This position can be varied Oust as shown in the firstembodiment, by the use of at least an additional coil providing at leastone intermediate position) to adjust for the amount of purged vapor theengine can handle at a given time.

FIG. 5 shows a diagram of an entire vapor management system, includingthe valve pictured in FIGS. 2-4 (1), a fuel storage tank (2), an engineintake manifold (3), a vapor recovery canister (4), fluid communicationlines (5), the fluid communication between the valve (1) and the fuelstorage tank (2) being made via a liquid/vapor discriminator (6). Avapor recirculation line (8) is shown to be in vapor communication withthe fuel storage tank (2) and the filler pipe (9) selectively based onthe valve position. In addition, an electronic communication line isshown (7). This line may be used to receive signals from the enginecontrol module specifying a valve position, which are then processed byan integral signal conditioner on the valve. The communication lineshown (7) could also consist of a number of power sources and a groundto energize the appropriate coils to make the valve function properly. Athird scenario for the communication line (7) is where it would connectto a separate fuel system processor. Note that a one-way check valve maybe necessary between the engine intake manifold and the valve toeliminate the possibility of back flow on engine deceleration.

1-10. (canceled)
 11. An electronically controlled electromechanicalvalve having at least three ports through which a fluid can flow and atleast three different stable positions in which at least two ports arein fluid communication, the valve comprising: a stationary outer housingcomprising at least three bores; a translating inner section thattranslates along a primary axis of the outer housing and comprisesadequate bores defining, with the bores of the housing, the at leastthree ports of the valve; and an electrical actuating system controlledby an electronic controller and configured to switch the valve from oneposition to another by translating the inner section along its axis. 12.The valve according to claim 11, further comprising an additional closedposition, in which none of the three ports are in fluid communication,and which is held by a suitable default mechanism configured to ensurethat the system is sealed in an event of electrical power loss.
 13. Thevalve according to claim 11, wherein the electrical actuating systemcomprises at least two coils fixed on the stationary outer housing andat least one magnet fixed on the translating inner section, the coilsbeing coupled to a power generator configured to energize the coils, togenerate an electrical current to circulate through the coils, inresponse to a signal from the electronic controller, so that eachposition of the valve is associated with a given coil being energizedand attracting the magnet to it.
 14. The valve according to claim 11,wherein the electrical actuating system comprises at least two magnets.15. The valve according to claim 11, wherein the electrical actuatingsystem comprises a motor placed at either end of the valve, whichtranslates an inner section of the valve and puts it in given positionsin response to a signal from the electronic controller.
 16. A fuelsystem vapor management unit for an internal combustion engine, the unitcomprising a valve according to claim
 11. 17. The unit according toclaim 16, wherein one position of the valve ensures complete flowcommunication between a fuel tank and a vapor recovery system and thetwo other positions ensure respectively complete and partialcommunication between the vapor recovery system and the engine.
 18. Theunit according to claim 16, wherein the valve comprises at least anadditional port to be connected to a vapor recirculation line extendingto the filler pipe.
 19. The unit according to claim 18, wherein thevalve comprises at least four ports to be connected respectively to thefuel tank, to a canister, to an engine, to a passage of large diameterto the vapor recirculation line, and to a passage of small diameter tothe vapor recirculation line or another vapor recirculation line. 20.The unit according to claim 19, further comprising a second port to beconnected to the fuel tank.